Removal of wool from animal skins



Patented June 25, 1935 UNITED STATES PATENT I OFFICE No Drawing. Application May 7, 1934, Serial No. 7%,392

11 Claims.

My invention relates to the recovery of fur and hair from skins of animals, particularly the recovery of wool from scraps of sheepskin.

In the fur trades, scraps of sheepskin are obtained in different manufacturing and tailoring processes and this wool, if not recovered, represents a considerable economical loss. It is known that wool can be removed from sheepskin by digesting the skin with a dilute solution of sulphuric acid, thereby liberating the wool which can thereafter be treated in various ways. This process, however, is applicable to only a relatively small proportion of cases. When the skin has not been tanned at all, or when it has been aluminum tanned, the simple dilute sulphuric acid process is fairly satisfactory. On all other tanned skins, such as chrome and bark tanned skins, the simple sulphuric acid treatment heretofore known in the art will produce a wool having a dark reddish brown shade. Such a wool is almost valueless except for inferior grades. of fabric, for example, which may be left undyed or dyed very dark colors.

By my process, I treat chrome and bark tanned sheepskin and sheepskin scraps to recover a wool that is practically white and can be used in the same way that ordinary grades of Wool are used in spinning, weaving and the like, and can be dyed any desirable shade without difficulty.

In carrying out the invention, I take a dilute solution of sulphuric acid in water, preferably from a 2 to 4% solution, and add thereto about 10% by weight of chrome tanned sheepskin scrap based on the total weight of water. This is boiled approximately ten to thirty minutes, the exact amount of time depending uponconditions. During the process, scrap metal is added, preferably non-ferrous white scrap metal such as aluminum filings, zinc dust, zinc filings, magnesium and the like, the metal having the eifect of liberating hydrogen during the process. The boiling is continued until substantially all of the leather has been dissolved sufificiently to permit the wool to come to the top.

The wool is now gathered and washed and is of a reddish brown color. It is now placed in approximately double the amount of water used in the first step of the process, to which water has been added about of a relatively mild alkali. Suitable alkalis are borax, sodium silicate, ammonium carbonate, tri-sodium phosphate, soda ash, and the like.

To safeguard the wool, it is usually desirable to use a buffer with the alkali. About of buffer based on the liquid is usually ample to prevent (Cl. 92ll) gelatinizing of the wool. Should a harsher type of alkali be used, the proportion should be less and/or the amount of the buffer increased. The best results, however, are obtained with a relatively mild alkali such as borax.

The amount of buffer used will be modified, depending upon the particular buifer used. If ordinary soaps are employed, about /4% is suitable. Buffers like gums, glues, urea, etc., may be used generally in somewhat smaller proportions. With some types of colloidal buffers, only a very small amount is suifi'cient, particularly with some a1- kalis, to have a suitable buffer action and prevent gelatinizing of the hair.

The reddish brown wool is boiled in this second solution for a short time until the solution takes on an intensely colored appearance from the wool. The wool is now allowed to rise to the top, is taken out and rinsed again with water.

After this treatment, as a rule, the wool will still be found to have a slight bluish pink color. This is usually readily removed by washing the wool thoroughly with about a one-half percent solution of sodium bisulphite or other reducing agent. After the treatment of the sodium bisulphite, the wool is again washed and dried, after which it is ready to be processed in the usual way that virgin grades of wool are handled. The wool resulting from this treatment ranges from a practically pure white color to a faint tan shade. It will not turn red on treatment with alkali. It is found to retain its suppleness when treated by this process and is of a high grade quality, greatly superior in every respect to the darkly colored wool obtainable by simple sulphurio acid treatments known to the trade.

Although the invention is described as taking place in a number of steps, those skilled in the art understand that in the practical carrying out of the process, continuous operations may be used with considerable facility, particularly where large scale operations are carried on. In other words, the process lends itself to either batch or continuous treatment, depending upon the type of equipment and the like most conveniently applicable in a given case.

The invention has been described as applicable to the treatment of wool, but obviously it may be used to recover any type of animal hair or fur from scraps of skin. Indeed it is not limited to use on scraps but for other purposes it is practically valueless as chemically there is no reason for removing wool by this method from large pieces of skin. Although the invention is of principal value in the treatment of scraps The term wool is used in the claims, therefore, to include any hair, fur, or woollike substance growing out 01' animal skin.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. The method of recovering wool from dyed animal skin, which includes the step of boiling the skin in a dilute solution of a mineral acid to which non-ferrous metal in finely divided form has been added. I v

2. The method of recovering wool from animal skin, which includes the step of treating the skin with a mineral acid solution to free the wool from the skin, and thereaiter treating said wool with a dilute solution oi. an alkali containing a butler.

3. The method 01' recovering wool from animal skin, which includes the step of treating the skin with a mineral acid solution to tree the wool from the skin, treating the wool with a di' lute solution of an alkali containing a butler, and thereafter washing said wool with a dilute's'olution of a reducing agent.

4. The method of recovering wool from animal skin, which includes the step of treating the skin with a mineral acid solution to free the wool from the skin, treating the wool with a dilute solution of an alkali containing a bufier, and thereafter washing said wool with a dilute solution of sodium bisulphite.

5. The method of recovering wool from animal skin which comprises boiling the skin in a dilute acid solution until the wool is released from the skin, treating the resulting wool with a solution of a mild alkali containing a butter, and washing the wool with a dilute solution of a reducing agent.

6. The method of recovering wool from animal skin which comprises boiling the skin in a dilute acid solution until the wool is released 2,005,746 of sheepskin, it is not limited to this specific use.

from the skin, treating the resulting wool with a solution of a mild alkali containing a butler, and washing the wool with a dilute solution 01' sodium bisulphite.

'7. The process for recovering wool from animal skin which comprises boiling .the skin in a dilute solution 01' mineral acid to which a nonferrous metal has been added to tree the wool from the skin, and treating the resulting wool with a hot solution of a mild alkali and a bufler.

8. The process for recovering wool from animal skin which comprises boiling the skin in a dilute solution oi! mineral acid to which a nonferrous metal has been added to free the wool from the skin, treating the resulting wool with a hot solution 01. a mild alkali and a buifer, and washing the wool with a solution of a reducing agent. 9. The process for recovering wool from animal skin which comprises boiling the skin in a dilute solution of mineral acid to which a nonferrous metal has been added to fre the wool from the skin, treating the resulting wool with a hot solution of a mild alkali and a buffer, and washing the wool with a solution of sodium bisulphite. I

10. The process for recovering wool from animal skin, which comprises boiling the skin with a dilute solution of sulphuric acid to which a small amount of comminuted magnesium has been added to remove the wool from the skin, treating the wool with a hot solution of an alkali of about concentration to which about of urea has been added as a buffer, and then washing the wool with a /2% solution of sodium bisulphite.

11. The process for recovering wool from animal skin, which includes the steps of treating the recovered wool with a hot alkali solution, and washing with a solution of a reducing agent.

' WOLF KRITCHEVSKY. 

